Hi.
We have 2 CUCMEs with SCCP and SIP phones in mixed mode at each CUCME.
These 2 are connected via H323.
CUCMEs are 4331 with Fuji-16.9.4(MD) IOS and have identical configuration.
In below call flows we can hear successfully MoH no matter which side starts the call.
SCCP Phone1 <=> CUCME1 <=> H323 <=> CUCME2 <=> SCCP Phone2 and SCCP Phone1 or SCCP Phone 2 presses on Hold.
SCCP Phone1 <=> CUCME1 <=> H323 <=> CUCME2 <=> SIP Phone2 and SCCP Phone1 presses on Hold.
In below call flows and vise versa we do NOT have MoH no matter which side starts the call..
SIP Phone1 <=> CUCME1 <=> H323 <=> CUCME2 <=> SIP Phone2 and SIP Phone1 or SIP Phone2 presses on Hold.
SCCP Phone1 <=> CUCME1 <=> H323 <=> CUCME2 <=> SIP Phone2 and SIP Phone2 presses on Hold.
In conclusion whenever a SIP Phone presses on Hold the other side can't hear MoH.
What I've seen is when the problem occurs and I do "show voip rtp connections" the Remote Side IP is 0.0.0.0
On the contrary when I see the output of the same command and Hold button is pressed by a SCCP phone the Remote Side has the CUCMEs IP.
When I configure a SIP Trunk between the 2 CUCMEs with the rest configuration remaining the same all the problems are solved but the case is to have them work via H323.
The above tests have been made with codecs G729r8 or G711alaw between the 2 CUCMEs with the same exact results.